Hydrocarbons, Crude Oil, Alkanes, Alkenes(Organic Chemistry Part 1) Flashcards
What is an organic compound
A compound which contains carbon
What is a hydrocarbon
A molecule
that consists of hydrogen and carbon atoms
ONLY
Why are molecular formulas rarely used in organic chemistry
Because they do not show anything about the bonding in a molecule
Definition of homologous series
Group of organic compounds
That have similar chemical properties
BECAUSE they have the same functional group
What is a functional group
An atom or group of atoms that determine the chemical properties of a compound
Molecular formula definition
Actual number of atoms in a molecule
Structural isomer definition
Molecule with the same molecular formula but different structural formula
A student carries out an experiment with pentanoic acid. If she uses another carboxylic acid to carry out the same experiment, will it react the same or differently and why
Will react the same because compounds in the same homologous series react in similar ways due to having the same functional group
If I have an isomer with a different functional group, will it have the same or different chemical and physical properties?
Different
Which alkanes do not have isomers and which do
Methane, ethane, propane
But butane does
What is the order of alkanes
Methane, ethane, propane, butane
What is the functional group of an alcohol
-OH
(Hydroxyl group)
What is the functional group of a carboxyl acid
-COOH
(Carboxyl group)
What is the functional group of an alkane
And an alkene
Alkane—-) C-C
Alkene—-) C=C
Name the order of alkenes
Ethene
Propene
Butene
Discuss alkenes and their isomers
Ethene does not have isomers
And propene does not have isomers which are alkenes(because they have no carbon-carbon double bond)
What is the general formula of an alkene
CnH2n
General formula of an alkane
CnH2n+2
Are alkanes saturated or unsaturated
Saturated
(Single bonds)
General formula of Alkane and Alkene
Alcohol and Carboxylic acid
ALKANE: ALKENE:
CnH2n+2 CnH2n
ALCOHOL: Carboxylic acid
CnH2n+1OH CnH2nO2
How was crude oil formed
From the remains of marine animals over millions of years
Explain the volatility of hydrocarbons as their chain length increases
Volatility is how easily it evaporates
So as chain length increases
Volatility increases because
Intermolecular forces of attraction are stronger so less likely to evaporate into a gas
Describe how five physical properties of hydrocarbons change as chain length increases
Becomes more viscous
Boiling point increases
Becomes darker
Becomes less volatile
Becomes less likely to burn
Give one reason why when it comes to combustion of hydrocarbons, smaller chain molecules are better to use than larger chain molecules
Because smaller chain molecules burn more easily
Give a property of ethane and propane that show they are in the same homogenous group
The same general formula
What is a fraction
Groups of hydrocarbons
With similar chain length
And with similar boiling points
What is crude oil
a mixture
of hydrocarbons
Of different chain lengths
How does bitumen form
Contains very large chain Hydrocarbons
And boiling point is too high to be boiled (into a vapour at the start of the process)
So remains a liquid
And is released through the fractionating column and used to make bitume.
What is petroleum another word for
Crude oil
Fill in the gaps:
When the hydrocarbons reach part of the column where the temperature is …. than their … they… into a…
lower
Boiling
Condense
Liquid
Explain what happens to long hydrocarbons during fractional distillation
They have long chain lengths
And so high boiling points
So remain at the bottom of the column
And condense earlier on
Because much hotter at the bottom
Why do large chain hydrocarbons condense earlier than when short chain hydrocarbons condense
Because the column is much hotter at the bottom
And long chain hydrocarbons are condensed there
As they have higher boiling points
Explain what happens to short chain hydrocarbons during fractional distillation
They are have shorter hydrocarbon chain lengths
And so have low boiling points
And so condense at the top of the column
Later on
Because it is much cooler
What aspect of the factional distillation column allows gases to be condensed at different times
The temperature gradient
Does each fraction in fractional distillation column have saturated or unsaturated hydrocarbons
May have either
Why does the top of the column have gases taken from them
Because these are very short chain molecules
Which have very low boiling points
And the fractionating column is not cool enough the condense these into liquid
So they remain in gas form
Explain the process of fractional distillation of crude oils:
1)Crude oil is boiled so that it vaporizes into a gas
2)liquid part called bitumen is drained out + colum contains temperature gradient
3)So vapors rise and longest hydrocarbon chain, condenses into a liquid first, as highest boiling points, at the bottom of the column as it is the hottest,
4)shortest hydrocarbon chains condense into a liquid last, as lowest boiling points, at the top of the column, as it is coolest,
5)vapors with very short hydrocarbon chains do not condense because very low boiling points and so are collected at the top as gases
6) bubble caps separate the Fractions + prevent the vapour from falling down, and mixing with others
The boiling point can also be referred to as:
The condensation point
Because boiling is just the opposite of condensation
(So it occurs at the same point)
What is another word for petrol
Gasoline
What is paraffin often referred as
Kerosene
Give six names of the fractions in fractional distillation and their uses
(From top to bottom)
Refinery gases—) domestic heating and cooking
Petrol—) fuel for cars
Kerosene—) fuel for jet planes + paraffin for small lamps
Diesel oil—) fuel for buses, lorries
Fuel oil—) fuel for ships + industrial heating
Bitumen—-) surfacing roads
Which fraction has larger hydrocarbon chain length
Kerosene or fuel oil?
Fuel oil
Which fraction has smaller hydrocarbon chain length?
Diesel oil or petrol
Petrol
Which molecules are refinery gases a mixture of?
Methane, ethane, propane, butane
Which is more viscous and explain why
Kerosene or diesel oil?
And why?
Diesel oil
Because larger hydrocarbon chain length
and so stronger intermolecular forces of attraction
So flow less easily
Which is less volatile?
Fuel oil or petrol?
And why
Fuel oil
Because larger hydrocarbon chain length
So stronger intermolecular forces of attraction
So more difficult to evaporate into a gas
Why does the fractionating column contain bubble traps
To prevent the fractions from mixing
What is a fuel?
A substance that when burned, releases heat energy
What is one of the major hydrocarbons present in petrol?
Octane
What is one of the major hydrocarbons in natural gas?
Methane
State the word equation for when a hydrocarbon is completely combusted
Hydrocarbon + oxygen —-) carbon dioxide + water
Word equation for incomplete combustion for up to 4 products
Hydrocarbon + oxygen —-) carbon dioxide + carbon monoxide+ water+ soot
When a fuel is combusted, state which products will be produced depending on if
A small amount of oxygen is used:
A medium amount of oxygen is used:
A large amount of oxygen is used
Small: soot
Medium: carbon monoxide
Large: carbon dioxide
When conducting an experiment to investigate complete and incomplete combustion, what colour will the flame be if complete combustion, and what colour will it be if incomplete combustion?
Blue if complete combustion
Orange if incomplete combutsion
Describe how carbon monoxide is a danger
Reduces the ability of red blood cells to carry oxygen around the body by binding with haemoglobin
+ can make you faint or die
What colour and smell is carbon monoxide?
Colourless and Odourless
Two products of incomplete combustion
Soot and carbon monoxide
Why are hydrocarbons good to use as fuel?
Because they produce large amounts of heat energy when burnt
Where are nitrogen oxides usually produced and why
From car engines
Because the temperature is high enough for oxygen in the air to react with nitrogen in the car
Name the two gases responsible for acid rain and where they are produced from
-sulfur dioxide: sulfur impurities from the burning of fossil fuels
-oxides of nitrogen: combustion in car engines
How are sulfur impurities turned to acid rain?
Sulfur impurities in fossil fuels react with oxygen in the air to form sulfur dioxide
When water and oxygen in the air react with sulfur dioxide, this produces sulfuric acid
Why is rain naturally acidic
Because it has carbon dioxide dissolved into it
Formula of sulfuric acid
And
Formula of sulfurous acid
Sulfuric acid—-) H2SO4
Sulfurous acid—) H2S03
Formation of sulfurous acid balanced symbol equation
SO2(g) + H20(l) —-) H2S03(aq)
Formation of sulfuric acid balanced word equation
2SO2(g) + 2H20(l) + O2(g) ——) H2SO4(aq)
Formation of nitrogen oxide balanced symbol word equation
N2(g) + O2(g) ——) 2NO(g)
Give three consequences of acid rain:
- kills fish in lakes
- damages trees
-corrodes limestone and metal buildings
Reaction between limestone and sulfuric acid
CaCO3(s) + H2SO4(aq) —-) CaSO4(s) + H2O(l) + CO2(g)
Which two acids are the cause of acid rain
Nitric acid
Sulfuric acid
Word equation of when sulfuric acid corrodes marble or limestone buildings:
Calcium carbonate + sulfuric acid —-) calcium sulphate + water + carbon dioxide
Give two solutions to preventing adverse effects of acid rain
Use sulfur scrubbing in gases in power stations
Or
Use a catalytic converters in a car
Explain What is cracking
Process in which long chain alkanes
are broken into smaller chain alkanes
and alkenes
Using heat of 600-700degrees
and a catalyst Like silica and aluminum
Explain why cracking is performed (4)
Crude oil contains a surplus of Long chain molecules
Cracking howver can produce Short chain hydrocarbon molecules
Short chain molecules can be produced, which are more useful and in higher demand
Short chain molecules also burn more cleanly
Alkenes produced can be used to make polymers
Suggest one reason why long chain hydrocarbons are not in demand
Because they are not easily flammable
So will not form good fuels
What type of chemical reaction is cracking?
(You could say two types)
Thermal decomposition
Endothermic reaction (absorbs heat)
Name two substances often used to produce petrol
Kerosene
Fuel oil
Name three substances that cracking can produce
Small chain alkenes
Small chain alkanes
Hydrogen
A student places liquid paraffin inside some mineral wool and put some porous pot next to it in a test tube . She then connects two heat sources on the bottom and connect the test tube to a delivery tube with downwards displacement jar.
Explain how this demonstrates the process of cracking
Liquid paraffin is the large chain alkane
The first heat source helps to break down the alkane and the porous pot is the catalyst which breaks the alkenes down through thermal decomposition
The second heat source is used to vaporize the liquid paraffin to a gas
This is collected in the Downwards displacement jar as gaseous alkene and alkane
What is the difference between thermal and catalytic cracking
Catalytic cracking involves both a catalyst and heat
Thermal cracking requires only heat but is done at much higher temperatures
Give two properties of a homologous group
-have same chemical properties BECAUSE same functional group
-show a gradation (trend) in physical properties
Comment on the boiling points of the alkanes
Boiling point increases in a REGULAR WAY as chain length increases
What state is pentane in at room temperature
Liquid
What state are the first four alkanes in at room temperature
Gas
Comment on organic compounds and combustion
All organic compounds can combust
Suggest why hydrogen is unlikely to be formed as a product of combustion reactions
Because it is highly flammable
(As it’s very reactive)
What is produced when an alkane reacts with plenty of oxygen
Carbon dioxide and water
Word equation for methane and bromine reacting in presence of U.V light
Methane + Bromine —-) Bromomethane + Hydrogen Bromide
Symbol equation for methane and bromine reacting in U.V light
CH4(g) + Br2(g) —-) CH3Br(g) + HBr(g)
Word equation for reaction of methane and chlorine
Methane + chlorine —-) chloromethane + hydrogenchloride
Which alkane reacts with bromide to produce two isomers, and what are the names of the two isomers
Propane
1-Bromopropane
2-Bromopropane
What happens when a mixture of bromide and methane is exposed to sunlight and why
It loses its orange color because a substitution reaction has taken place
Write the structural formula for reaction between ethane + chlorine in ultraviolet light
CH3CH3(g) + Cl2(g) —-) CH3CH3CL(g) +HCL(g)
(molecular formula just in case C2H6 + Cl2 —-) C2H5CL + HCL )
Which alkenes are gases at room temperature and which alkenes are liquids
Ethene, propene and bromene are all gases
And then the alkenes with more than 5 carbon atoms are all liquids
Explain why there is no such thing as methene (or alkene with only 1 carbon atom)
Because the alkenes are unsaturated compounds and would not be able to form double bonds with only one carbon atom
(Because hydrogen can only form one bond so you wouldn’t be able to have C=H
Write the structural formula of ethene + bromine (water)
C2H4(g) + Br2(aq) —-)CH2Br-CH2Br(l)
When ethene reacts with bromine, give the word equation and describe the states that all of the reactants and products are in
Ethene(colourless gas) + Bromine(orange liquid in aqeous state) —-—-) 1,2dibromoethane (colourless liquid)
When an alkene becomes an alkane with the addition of bromine, what type of reaction is this
An addition reaction
Write the structural formula of the reaction between propene and bromine (water)
Addition reaction:
C3H6(g) + Br2(aq) —-) CH2BrCHBrCH3(l)
( Remeber if using a displayed formula to work this out first, make sure you are conscious of the double bond in the propene molecule and how many hydrogens are attached to it)
Word equation with state symbols between the reaction of Propene and Bromine
Propene(g) + Bromine(aqueous) ——) 1,2dibromopropane (l)
Is an alkene more reactive or an alkane, and explain why
Alkenes are more reactive due to the presence of the carbon-carbon double,
And so a higher electron density
When adding an alkane to bromine water, and then an alkene to bromine water, state what the test tube looks like for each one and why
Adding an Alkane to bromine water, the orange bromine water will still be there
Because alkanes do not contain a carbon-carbon double bond and so can not decorlize bromine water in an addition reaction
Adding an alkene to bromine water, the orange bromine water becomes colourless
Because alkenes contain a carbon-carbon double bond and so can decolonize bromine water in an addition reaction
Difference between hydrogenation and hydration reactions of alkenes
In a hydrogenation reaction, there is only the addition of hydrogen
Whereas in a hydration reaction, there is the addition of water, and an alcohol is formed AND a catalyst is required, like phosphoric acid
(Remember that both reactions are addition reactions)
A compound has the same general formula of an Alkene, but does not decolourize bromine water. Explain why
Is an isomer, so possibility that it does not contain a carbon- carbon double bond
(Remember that isomers can have same general formula but can have different structures which do not consist of double bonds)
What is the name of the type of reaction when an alkene reacts with hydrogen to form an alkene
Addition
Hydrogenation
What is the name of the type of reaction when an Alkane produces an Alkane and alkene
Thermal decomposition
The alkane tridecane can be cracked to produce octane and two different alkenes.
Complete the equation to show the formulae of the two alkenes.
C13H28 + C8H18——-)
C2H4 + C3H6
Give two conditions of cracking
Must use heat of 600-700 degrees
Must use a catalyst such as silica
Definition of a saturated compound
And then an unsaturated compound
Contains ONLY Carbon-Carbon single bonds
Contains a carbon-carbon double bond
What is the chemical name for soot
Carbon
Balanced symbol equation for nitrogen combusting with oxygen
N2(g) + O2(g)——-) 2NO
T
How is carbon monoxide in the exhaust fumes formed
There is incomplete combustion of octane(the fuel) as it burns in an insufficient amount of oxygen
Complete the combustion word equation
Octane + _______ ———) carbon dioxide. + _____
Oxygen
Water
Ethane (C2H6) is used as a starting material to manufacture addition polymers. It is first cracked to form ethene (C2H4).
(a) Identify the fuel that also forms in this reaction.
Hydrogen
Explain how the formulae of ethane and ethene compounds show that they are in different series.(2marks)
They have different general formula(1)
Where ethene has formula C2H2n, WHEREAS ethane has a DIFFERENT formula which is C2nH2n+2(1)
If butane is bubbled through bromine water, there would be no change in colour.
But state one condition that could be applied so that there was a change
Presence of UV light
The equation for the complete combustion of octane is
C8H18 + 12.5O2 ——) 8CO2 + 9H2O
Write a chemical equation for the incomplete combustion of octane
C8H18 + 8.5O2 → 8CO + 9H2O
(Rmeber just change the carbon dioxide to carbon monoxide and then balance from there)
Give a reason why gasoline is more in demand than fuel oil
Because gasoline is used for cars which are more common than shops used for fuel oil
Give two reasons why obtaining making by obtaining ethene from cracking is better than obtaining ethanol from fermentation
Cracking is much faster
Cracking has a higher percentage yield
Give two reasons why obtaining ethanol by fermentation is better than obtaining ethanol from the cracking of ethene
Sugar used in fermentation is a renewable source
Uses less energy
State the catalyst used and the amount of temperature required to create ethanol from the hydration of ethene
Phosphoric acid
250-350 degrees
Why is incomplete combustion a problem with a larger alkene like butene than ethene
Because it would need even more oxygen to react, (so basically then there would be even less oxygen and incomplete combustion would be more severe)
Describe the difference of covalent bonds between crude oil and kerosene
Crude oil has more covalent bonds than kerosene
Give four differences between crude oil and kerosene in terms of properties
Crude oil has a wider range of boiling points than kerosene
Crude oil is more viscous(flows less easily) than kerosene
Crude oil has more covalent bonds than kerosene
Crude oil has a wide range of sizes of molecules whereas kerosene all have the same size
